1. Field of the Invention
The invention relates to the field of microscope systems, and more specifically to a method and system for structured illumination microscopy. In particular, the invention relates to an improved method and system for providing a 3D height map of a specimen.
2. Description of Related Art
EP 2 327 956 A1 discloses an optical sensor which is used to determine the range (distance) of individual features of a three-dimensional structure. The sensor has a spatially modulating periodic patterned light source which illuminates the specimen. An array of detector elements is used to detect images of the projected pattern. While the specimen is moved through the focal position, the pattern is varied for at least three spatial modulation phases when moving the spatial periodic light pattern in a direction perpendicular to the optical axis of the optical sensor, parallel to the direction in which the periodic pattern is periodic. Analyzing the output signal of the detector includes for each spatial position of the detector the determination of the amplitude of the signal detected during the scanning and determining the scanning location where the amplitude has a maximum.
US 2010/0135547 A1 discloses systems and methods for optical sectioning microscopy with structured illumination. A light source generates a light beam with a spatial pattern for successively illuminating a sample at each phase of a plurality of phases. A sinusoidal pattern in multiple directions is used. The pattern is moved in both the x- and y-direction at a single Z-location, and the patent gives an evaluation method for obtaining an axially sectioned image.
US 2012/0140243 relates to methods for forming a three-dimensional image of a test object. The methods include directing light to a surface of best-focus of an imaging optic, where the light has an intensity modulation in at least one direction in the surface of best-focus. The test object is scanned relative to the imaging optic so that a surface of the measurement object passes through the surface of best-focus of the imaging optic as the test object is scanned. For each of a series of positions of the test object during the scan, a single image of the measurement object is acquired using the imaging optic. The intensity modulation of the light in the surface of best-focus is different for successive images. A three-dimensional image of the test object is formed based on the acquired images. The sequence and evaluation of the images are not disclosed.
In the prior art, no solution is provided for the creation of a 3D height map of a specimen with good Z resolution, and highly independent of the surface structure, where neighboring points may have a different height and reflectivity, and local slopes may be present.